Magnetic Properties of Cu2+ Substituted Ni–Zn Nano-Crystalline Ferrites Synthesized in Citrate-Gel Route

The Nano-crystalline divalent copper ion substituted Ni–Zn ferrites having chemical formula Ni0.5Zn0.5−xCuxFe2O4 (where x = 0.05 to 0.25 in steps of 0.05) were prepared by citrate gel auto-combustion method. The X-ray diffraction study confirmed the single phase spinel cubic structure and the crystallographic studies indicate that the lattice parameter was observed to be decreased with increasing of Cu2+ concentration. Scanning Electron Microscopy was conducted to observe surface morphology and grain size/shape. Magnetic measurements were carried out using Vibrating Sample Magnetometer for magnetization and Impedance analyzer for permeability up to 15 MHz. Magnetization studies revealed that the incorporation of copper into the system modified the exchange interactions leading to gradual decrease in saturation magnetization. Highest saturation magnetization was observed for the base composition Ni0.5Zn0.5CuFe2O4 with 61 emu/g. There was an increase in coercivity and remanence with copper concentration. Frequency and temperature variation of inductance measurements were performed to understand the system behaviour at different threshold limits. Enhancement of initial permeability was observed up to the concentration x = 0.15 and its variation is observed to be grain size dependent. Temperature variation of permeability leads to Curie temperature, which was increased with increasing of Cu2+ concentration. All magnetic characteristics of the present system of nano crystalline ferrites displayed interesting deviations and reasons were well justified.